CVE-2025-48940

Published: Jun 2, 2025Modified: Jun 17, 2026

7.2

Vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Exploitability: 1.2 / Impact: 5.9

Source: security-advisories@github.com (Secondary)

Description

MyBB is free and open source forum software. Prior to version 1.8.39, the upgrade component does not validate user input properly, which allows attackers to perform local file inclusion (LFI) via a specially crafted parameter value. In order to exploit the vulnerability, the installer must be unlocked (no `install/lock` file present) and the upgrade script must be accessible (by re-installing the forum via access to `install/index.php`; when the forum has not yet been installed; or the attacker is authenticated as a forum administrator). MyBB 1.8.39 resolves this issue.

Affected (1)

Products: Mybb: Mybb

1 product

Configuration A

1 vulnerable

Vulnerable Software	Affected Versions
Mybb Mybb	Before 1.8.39

Related CWEs

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

References (3)

https://github.com/mybb/mybb/commit/6e6cfbd524d9101b51e1278ecf520479b64b0f00

Source: security-advisories@github.com

Patch

https://github.com/mybb/mybb/security/advisories/GHSA-q4jv-xwjx-37cp

Source: security-advisories@github.com

Vendor Advisory

https://mybb.com/versions/1.8.39

Source: security-advisories@github.com

ProductRelease Notes

Timeline

No history available yet.